The invention relates to a device with a prosthesis implantable in the body of a patient, especially in a blood vessel or other body cavity, and designed as a hollow body, said prosthesis being compressible against the action of restoring spring forces down to a cross section which is reduced relative to an (expanded) operating position, said prosthesis also automatically expanding to a cross section corresponding to the operating position following removal of the restraining forces effecting the compression.
Devices of this type are known, and serve for percutaneous implantation of vascular prostheses in particular. Prostheses which are introducible percutaneously and expand in the lumen are either expandable mechanically by means of a known balloon catheter from a small radius to the larger radius to hold a vascular lumen open, or they expand automatically following previous compression prior to implantation by spring force, due to spring pretensioning generated during compression.
Various systems are already known for inserting self-expanding vascular prostheses which are under spring force into the body of a patient, and to implant or anchor them in the vessel by removing the restraining force.
The commonest method, which is described in EP-A-0 183 372, consists in compressing an endoprosthesis, made in the form of a tubular hollow body, to a reduced cross section and then pushing it in the compressed state, using a so-called pusher, through a catheter previously introduced into a vessel until they are in the correct position in the vessel. However, this system suffers from the disadvantage that a considerable expenditure of force is required to push the prosthesis through the catheter because its displacement is counteracted by considerable frictional forces.
Another method (not confirmable by publications) consists in retracting a sheath covering the endoprosthesis and holding the latter together, in the vessel at the implantation site. Here again there is the disadvantage that high frictional forces must be overcome. Moreover, the tube system is quite rigid because of the sheath covering the prosthesis, making introduction into a vessel through curves very difficult.
In another system (U.S. Pat. No. 4,732,152) a woven and spring-tensioned prosthesis is held together in the compressed state by a double sheath, sealed at the distal end. This sheath is retracted from the folded prosthesis like a stocking being pulled off the foot of a wearer. To reduce the friction which then occurs, liquid can be introduced between the two sheath layers. This system, which initially appears elegant because of the reduction of the frictional resistances, is extremely cumbersome to handle however and requires two persons to operate.